A polyarylene having sulfonic acid groups is useful as a polyelectrolyte for proton-exchange membrane fuel cell. As a process for producing it, a process using a diphenyl dihalobiphenyldisulfonate as a monomer (e.g. Macromol. Rapid. Commun., 15, 669-676 (1994) and Polymeric Materials; Science & Engineering, 2003, 89, 438-439) has been known.